Heat exchanger

ABSTRACT

A heat exchanger is provided. The heat exchanger includes a stack assembly with a plurality of plates and a plurality of frames arranged in an alternating stacked relationship with the plates along a predetermined direction. Each of the plates has a plurality of first openings and each of the frames has a plurality of second openings. A plurality of first and second fluid channels extends through the stack assembly along the predetermined direction and through the plurality of first and second openings. A first fluid flow path includes a first inlet channel in fluid communication with the plurality of first fluid channels, and a first outlet channel in fluid communication with the plurality of second fluid channels. A second fluid flow path is in thermal contact with the first fluid flow path and fluidically isolated from the first fluid flow path.

CLAIM FOR PRIORITY

The present application claims priority from U.S. ProvisionalApplication Ser. No. 60/753,812, filed Dec. 23, 2005, which is fullyincorporated herein.

TECHNICAL FIELD

The present disclosure is directed to a heat exchanger, and moreparticularly to a stacked plate heat exchanger and method of assemblythereof.

BACKGROUND

Plate-type heat exchangers are used for certain industrial applicationsin place of fin and tube or shell and tube type heat exchangers becausethey are less expensive and easier to make than most forms of heatexchangers. In one form of such plate-type heat exchangers, a pluralityof primary surface plates are brazed together in a unitary structurewith spacer frames located between adjacent plates and traversing acourse adjacent to the plate peripheries. Flow of the two fluidsinvolved in heat exchange is through alternate layers defined by thebrazed plates. The space between the plates may be occupied byprotuberances or fins formed in the plates to increase turbulence orheat exchange in the fluid flow. All of the fluid flowing in a givendefined space is in contact with the plates to enhance heat transfer.

In order to handle larger heat loads, existing plate-type heatexchangers may be scaled up in size by adding more layers or usingdenser configurations of layers. However, one problem that arises withsome designs is that the pressure loss across the heat exchangerincreases. One technique used to decrease the pressure loss is totransversely supply each layer from a single conduit. The conduit issized to minimize any pressure drops. An example of such a heatexchanger is disclosed in U.S. Pat. No. 5,911,273 to Brenner et al.(“the '273 patent”). The '273 patent discloses a heat exchanger having astacked plate construction made of four distinct parts: a cover, a flowduct plate, a connection cover plate, and a connection plate. Theseparts are alternated and rotated in a stack assembly. A first fluidflows into the heat exchanger through a connection opening, into asingle connection conduit, then transversely through fluidicallyparallel layers. A second fluid has a similar flow pattern, with theheat exchange occurring across the parallel layers of the stackassembly.

While the configuration of the '273 patent attempts to decrease pressurelosses, it results in an increased manifold volume or supply conduitvolume to heat exchanger volume ratio. As the size or the number oflayers in the heat exchanger increases, the size of the manifold volumeincreases as well. For applications requiring a compact construction,this may prove to be unacceptable. In addition, there may be non-uniformheat exchange such that layers farthest from the supply conduit inletsmay receive less flow than layers closest to the supply conduit inlets.

The present disclosure is directed to overcoming one or more of theproblems set forth above.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure is directed to a heat exchanger.The heat exchanger includes a stack assembly with a plurality of platesand a plurality of frames arranged in an alternating stackedrelationship with the plates along a predetermined direction. Each ofthe plates has a plurality of first openings and each of the frames hasa plurality of second openings. A plurality of first and second fluidchannels extends through the stack assembly along the predetermineddirection and through the plurality of first and second openings. Afirst fluid flow path includes a first inlet channel in fluidcommunication with the plurality of first fluid channels and a firstoutlet channel in fluid communication with the plurality of second fluidchannels. A second fluid flow path is in thermal contact with the firstfluid flow path and fluidically isolated from the first fluid flow path.

In another aspect, the present disclosure is directed to a method ofmaking a heat exchanger including the steps of providing a plurality ofplates having a plurality of first openings and providing a plurality offrames having a plurality of second openings. The method also includesthe steps of alternately stacking the plates with the frames along astack direction and aligning the plurality of first openings with theplurality of second openings to define a first and second plurality offluid channels extending through the plates and the frames along thestack direction. The method also includes the steps of coupling a firstmanifold to each of the first plurality of fluid channels along thestack direction and coupling a second manifold to each of the secondplurality of fluid channels along the stack direction. The method alsoincludes the step of sealingly interconnecting the stacked plates andframes to each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of one exemplary embodiment of aheat exchanger.

FIG. 2 is a plan view of a cover for the heat exchanger of FIG. 1.

FIG. 3 is a plan view of a frame layered on the cover of FIG. 2.

FIG. 4 is a plan view of a plate of the heat exchanger of FIG. 1.

FIG. 5 is a plan view of a frame, which is rotated 180 degrees about astack direction from the frame of FIG. 3, layered on the plate of FIG.4.

FIG. 6 is a plan view of a plate that is rotated 180 degrees about atransverse direction from the plate of FIG. 4.

FIG. 7 is a plan view of a frame layered on the plate of FIG. 6.

FIG. 8 is a perspective view of a tapered insert that may be placed inthe manifolds or fluid channels of FIG. 1.

FIG. 9 is a detail view of the plate of FIG. 1.

FIG. 10 is an exploded perspective view of another exemplary embodimentof the heat exchanger, shown with foam inserts.

FIG. 11 is a detail view of the inserts of FIG. 10.

FIG. 12 is a perspective view of a frame that may be used with anotherexemplary embodiment of a heat exchanger.

FIG. 13 is a plan view of the frame of FIG. 12.

DETAILED DESCRIPTION

Reference will now be made in detail to the drawings. Wherever possible,the same reference numbers will be used throughout the drawings to referto the same or like parts.

FIG. 1 shows a heat exchanger 10. Heat exchanger 10 includes a stackassembly 20 made up of alternating layers of plates 30 and frames 40, abottom cover 50, a top cover 60, and manifolds 82, 84, 86, and 88. Heatexchanger 10 is shown assembled along a stack direction 12 that isoriented vertically, but this is only for purposes of illustration.

Stack assembly 20 is made up of layers of plates 30 and frames 40. Asseen in FIG. 1, plates 30 are flat plates formed of a thin sheet ofmaterial such as stainless steel, aluminum, brass, copper, bronze, orany other material with desired heat transfer characteristics. Inaddition, while plates 30 are depicted as rectangular, other shapes mayalso be used. In one exemplary embodiment plates 30 have dimensions of279 mm long by 179 mm wide by 0.1 mm thick, although plates 30 of othersizes may also be used. Plates 30 may be formed by methods known in theart, such as stamping, laser beam cutting, water torch cutting, eroding,etc.

As seen in FIG. 4, a first and second row 34, 36 of openings 32 arepositioned along parallel edges of plate 30. Openings 32 in each offirst and second row 34, 36 are spaced a distance of “d” apart. In oneexemplary embodiment, openings 32 are symmetrically aligned on oppositeedges of plate 30, although other configurations may also be used.

In addition, as seen in FIGS. 1, 4, and 9, plates 30 are integrallyformed with a plurality of turbulators 38 arranged in an array 39. Asseen in FIG. 9, plates 30 may be formed such that adjacent turbulators38 have opposite configurations with respect to stack direction 12. Oneturbulator 38 a may project out of plate 30 along stack direction 12,while an adjacent turbulator 38 b may project into plate 30 along stackdirection 12. In one exemplary embodiment, turbulators 38 have a heightof 1 mm, or one half the thickness of frames 40. As seen in FIG. 4, theturbulators 38 may be oriented at an angle of “θ1” to a transversedirection 14, which is approximately twenty degrees in one exemplaryembodiment.

As seen in FIGS. 5 and 7, frames 40 are sized to have similar outerdimensions to that of plates 30, and may also be made of similarmaterials. Frames 40 also may have a thickness of approximately twicethe height of turbulator 38, which in one exemplary embodiment is 2 mm,although other thicknesses may be used. As seen in FIG. 3, frames 40also have a first and second row 44, 46 of alternating openings 42 andvoids 43 that are positioned along parallel edges. Openings 42 in eachof first and second row 44, 46 are spaced a distance of “2d” apart, andare enclosed within the interior periphery 41 of frame 40. Voids 43 arealso formed in the interior periphery 41 of frame 40 and are spaced adistance of “2d” apart, such that each opening 42 is spaced a distanceof “d” from an adjacent void 43. This spacing between voids 43 andopenings 42 is maintained for both first row 44 and second row 46. Inaddition, the openings 42 and voids 43 in first and second row 44, 46may be symmetrically aligned along parallel edges of frame 40, such thatthe openings 42 and voids 43 in the first row 44 are mirror images ofthe openings 42 and voids 43 in the second row 46. Openings 42 and voids43 are sized to match the openings 32 in plates 30, although they may beslightly increased or decreased to facilitate alignment and sealing.

As seen in FIG. 1, stack assembly 20 begins with a frame 40. A firstplate 30 is aligned on the frame 40. A second frame 40, which is rotated180 degrees about the stack direction 12 from the first frame 40, isplaced on the plate 30. A second plate 30, rotated 180 degrees about atransverse direction 14, is placed onto the frame 40. As seen in FIG. 6,the turbulators 38 of the second plate 30 are symmetrically disposedabout the transverse direction 14, such that “θ2” is equal to the “θ1”shown in FIG. 1. The stack continues in this fashion, alternating frames40 and plates 30, with successive frames 40 and plates 30 rotated 180degrees about a transverse direction 14 from the preceding one.

Stack assembly 20 is placed onto a bottom cover 50. As seen in FIG. 2,bottom cover 50 has a first and second row 54, 56 of openings 52positioned along parallel edges. Openings in first and second row 52 arepositioned a distance of “2d” apart. In addition, a series ridges 51 mayextend across an inner surface of bottom cover 50. Depending on theorientation, these ridges 51 may serve to direct the flow of fluidacross the cover, turbulate the water, and/or increase heat exchange.The openings 52 in first and second row 54, 56 of bottom cover 50 arelaterally offset a distance of “d”, such that the first and second rows54, 56 of openings 52 are not symmetric along the length of the cover.Bottom cover 50 may be sized with substantially the same outerdimensions as frame 40 or plate 30.

As seen in FIG. 1, a top cover 60 is placed at the top of the stackassembly 20. Top cover 60 has a first and second row 64, 66 of openings62 positioned on parallel edges. In one exemplary embodiment, top cover60 is identical to bottom cover 50. However, in assembling top cover 60to stack assembly 20, top cover 60 is rotated 180 degrees about atransverse direction 14 with respect to bottom cover 50. Other aspectsof top cover 60 are similar to bottom cover 50, shown in FIGS. 1 and 2and described above.

As the heat exchanger 10 is stacked, the alignment of openings 32, 42,52 and voids 43 in the plates 30, frames 40, and covers 50, 60 define aplurality of fluid channels 95, 96, 97, 98 that extend through the stackassembly 20 along the stack direction 10. Fluid channels 95, 96 aredefined in the first row 34, 44, 54, 64 of plates 30, frames 40, andcovers 50, 60, while fluid channels 97, 98 are defined in the second row36, 46, 56, 66 of plates 30, frames 40, and covers 50, 60. In oneexemplary embodiment, fluid channels 95, 96 alternate openings 32, 42,52, 62 and voids 43 throughout first row 34, 44, 54, 64, so that eachfluid channel 95 is adjacent a fluid channel 96. Similarly, fluidchannels 97, 98 alternate openings 32, 42, 52, 62 and voids 43throughout second row 36, 46, 56, 66, so that each fluid channel 97 isadjacent a fluid channel 98.

As seen in FIG. 1, each of manifolds 82, 84, 86, and 88 is positionedover the first and second row of openings 54, 56, 64, 66 of top andbottom covers 60, 50. Manifolds 82, 84, 86, and 88 each serve as fluidconduits. Manifolds 82 and 84 function as an inlet and outlet,respectively, for a first fluid, such as hot engine oil. Manifolds 86and 88 function as an inlet and outlet, respectively, for a secondfluid, such as coolant.

As seen in FIG. 8, tapered inserts 90 may be placed in manifolds 82, 84,86, and 88. In one exemplary embodiment of the present invention,inserts 90 are placed in the first and second fluid outlet manifolds 84and 88. These inserts serve to equalize the pressure drop across theheat exchanger so that there is a substantially equal flow and heatexchange between fluids across the length and height of the heatexchanger 10. Alternately, inserts 90 may be placed in the fluidchannels 95, 96, 97, 98 extending along the stack direction 12,designated as “h” and “c” in first and second row 34, 36 in FIG. 4. Theinserts 90 may be integrally formed with manifolds 82, 84, 86, and 88,or sealed to the manifolds 82, 84, 86, and 88 in a separate step.Inserts 90 may be made from stainless steel, aluminum, brass, copper,bronze, or other material with desired heat transfer characteristics.

FIGS. 10-11 illustrate another exemplary embodiment of the presentinvention. Foam inserts 100 are placed within the interior periphery 141of frames 140. Foam inserts 100 may be made from a porous metal orcarbon as described in U.S. Pat. Nos. 3,616,841 and 3,946,039 to Walz,U.S. Pat. App. No. 2004/0226702 to Toonen, or U.S. Pat. No. 6,673,328 toKlett. Inserts 100 have large surface area per unit volumes(approximately 1600 square feet/cubic foot).

These inserts may be placed in the interior periphery 141 of every frame140, or only used with alternate frames 140, as is shown in FIG. 10. Asis shown in FIG. 10, plates 130 are formed with only a single surface ofturbulators 38. Other aspects of heat exchanger 110 are similar to theheat exchanger 10 shown in FIG. 1 and described above.

In another exemplary embodiment, a gas to fluid heat exchanger (notshown) may be constructed by substituting layers of frames 340, as shownin FIGS. 12 and 13, with every other frame 40, 140 in heat exchangers10, 110 as shown in FIGS. 1 and 10. Similar to frames 40 and 140, frame340 has a first and second row 344, 346 of alternating openings 342 andvoids 343 that are positioned along parallel edges. A plurality oftransverse openings 348 extend through the voids 343 in both the firstand second row 344, 346. These transverse openings 348 permit atransverse flow 390 along the transverse direction 14 to flow past theturbulators 38 and through the frame 340, providing heat transfer toalternate plates 30, 130. These transverse openings 348 open the heatexchanger to ambient air, allowing for an air-to-fluid heat exchanger.Such a heat exchanger could also eliminate one set of manifolds.

Heat exchangers 10, 110 may be formed using a brazing operation. Beforeassembly, a flux is applied to the peripheries of each of manifolds 82,84, 86, 88; covers 50, 60, frames 40, and plates 30. Thin sheets ofsolder may be placed between each layer to ensure a solder sealextending around the entire periphery. After assembly, the heatexchanger 10, 110 may be clamped together and heated to form a sealedunit. Alternately, the heat exchanger 10, 110 may be formed from anyother technique known in the art, such as welding.

INDUSTRIAL APPLICABILITY

In operation, a first and a second fluid flow path 92, 94 are definedthrough the heat exchanger 10, 110. A first fluid, such as heated engineoil, follows first fluid flow path 92 and enters through manifold 82.From manifold 82, the first fluid next flows into the fluid channels 96extending through the stack assembly 20 defined by the first row 54 ofopenings 52 in the bottom cover 50 (as seen in FIG. 2, designated by“h”). From the flow channels, the first fluid flows through voids 43 inthe first row 44 of alternate frames 40, 140 flowing across theturbulators 38 of primary surface sheets or plates 30, 130. The flowpath 92 continues into voids 43 in the second row 46 of alternate frames40, 140 and back through fluid channels 98 extending through the stackassembly 20 (“designated by “h” in the second row 36 in FIG. 4). Flowpath 92 continues from the fluid channels 98 in the second row tomanifold 84, where it exits after being cooled by the heat exchange withthe second fluid.

Similarly, a second fluid, such as coolant, follows second fluid flowpath 94 and enters through manifold 86. From manifold 86, the secondfluid next flows into fluid channels 97 extending through the stackassembly 20 defined by the second row 56 of openings 52 in the bottomcover 50 (as seen in FIG. 2, designated by “c”). From the fluid channels97, the second fluid flows through voids 43 in the second row 46 ofalternate frames 40, 140 flowing across the turbulators 38 of primarysurface sheets or plates 30. The flow path 94 continues into voids 43 inthe first row 46 of alternate frames 40, 140 and back through fluidchannels 95 extending through the stack assembly 20 (“designated by “c”in the first row 36 in FIG. 4). Flow path 94 continues from the fluidchannels 95 in the second row to manifold 88, where it exits after beingheated by the heat exchange with the first fluid. Alternately, the firstand second fluid flow paths 92, 94 may be reversed. In addition, thefirst and second fluid inlets may feed into the upper manifolds 88, 84instead of the lower manifolds 82, 86, or any other combination. Fluidflow path 92 is fluidically isolated from fluid flow path 94.

Foam inserts 100 or turbulators 38 may also be used to increase the heatexchange that occurs across primary surface sheet or plate 30, 130.Additional heat exchange may also occur in alternating channels in eachof the first and second rows (as seen in FIG. 2, adjacent “h” and “c”).

It will be apparent to those having ordinary skill in the art thatvarious modifications and variations can be made to the disclosed heatexchanger without departing from the scope of the invention. Otherembodiments of the invention will be apparent to those having ordinaryskill in the art from consideration of the specification and practice ofthe invention disclosed herein. It is intended that the specificationand examples be considered as exemplary only, with a true scope of theinvention being indicated by the following claims and their equivalents.

1. A heat exchanger comprising: a stack assembly including: a pluralityof plates, each of the plates having a plurality of first openings; aplurality of frames arranged in an alternating stacked relationship withthe plates along a predetermined direction, each of the frames having aplurality of second openings; and wherein a plurality of first andsecond fluid channels extend through the stack assembly along thepredetermined direction and through the plurality of first and secondopenings; a first fluid flow path including: a first inlet channel influid communication with the plurality of first fluid channels; and afirst outlet channel in fluid communication with the plurality of secondfluid channels; and a second fluid flow path in thermal contact with thefirst fluid flow path and fluidically isolated from the first fluid flowpath.
 2. The heat exchanger of claim 1, wherein a plurality of third andfourth fluid channels are defined along the predetermined directionthrough the plurality of first and second openings; and the second fluidflow path includes a second inlet channel in fluid communication withthe plurality of third fluid channels and a second outlet channel influid communication with the plurality of fourth fluid channels.
 3. Theheat exchanger of claim 1, wherein the first inlet channel is configuredto provide substantially equal fluid flow to each of the first pluralityof fluid channels.
 4. The heat exchanger of claim 3, further comprisinga tapered insert in the first inlet channel.
 5. The heat exchanger ofclaim 1, wherein the second fluid flow path is substantiallyperpendicular to the predetermined direction.
 6. The heat exchanger ofclaim 1, wherein each of the plurality of plates has a first array ofturbulators on a first surface.
 7. The heat exchanger of claim 6,wherein each of the plurality of plates has a second array ofturbulators on a second surface.
 8. The heat exchanger of claim 1,wherein the plurality of first openings are aligned in a first and asecond row, the first and second rows are positioned along paralleledges of each of the plates, and each of the first openings in the firstrow and each of the first openings in the second row are positioned apredetermined distance apart.
 9. The heat exchanger of claim 8, whereinthe plurality of second openings are aligned in a third and a fourthrow, the third and fourth rows are positioned along parallel edges ofeach of the frames, and each of the second openings in the third rowsand each of the second openings in the fourth rows are positioned twicethe predetermined distance apart.
 10. The heat exchanger of claim 1,wherein the stack assembly includes a plurality of foam layers arrangedin an alternating stacked relationship with the plates and frames alongthe predetermined direction.
 11. The heat exchanger of claim 10, whereinthe plurality of foam layers are aluminum or carbon foam.
 12. The heatexchanger of claim 1 further comprising a top and a bottom coverpositioned on opposite sides of the stack assembly along thepredetermined direction, the top and bottom cover having a plurality ofthird openings, and wherein the first and second plurality of fluidchannels extend through the top and bottom cover through the pluralityof third openings.
 13. The heat exchanger of claim 12, wherein the topand bottom cover are substantially identical.
 14. A method of making aheat exchanger comprising: providing a plurality of plates, each of theplates having a plurality of first openings; providing a plurality offrames, each of the frames having a plurality of second openings;alternately stacking the plates with the frames along a stack direction;aligning the plurality of first openings with the plurality of secondopenings to define a first and second plurality of fluid channelsextending through the plates and the frames along the stack direction;coupling a first manifold to each of the first plurality of fluidchannels along the stack direction; coupling a second manifold to eachof the second plurality of fluid channels along the stack direction; andsealingly interconnecting the stacked plates and frames to each other.15. The method of claim 14, further comprising rotating alternate frames180 degrees about the stack direction.
 16. The method of claim 15,further comprising tapering the first manifold to provide substantiallyequal flows to each of the first plurality of fluid channels.
 17. Themethod of claim 14, wherein each of the plurality of plates has a firstarray of turbulators on a first surface and a second array ofturbulators on a second surface opposite the first surface, and furthercomprising rotating alternate plates about a second directionperpendicular to the stack direction.
 18. The method of claim 14,further comprising: providing a plurality of foam layers; and stackingthe foam layers with the plates and frames along a stack direction. 19.The method of claim 14, further comprising: providing at least one coverhaving a plurality of third openings; and aligning the plurality ofthird openings with the first and second plurality of fluid channelsextending through the plates and the frames along the stack direction.